Identification of Brittleness Distribution Based on Elastic Properties: A Case Study and Application

초록

Rock brittleness is a crucial indicator of fracture complexity and potential microearthquake events, making it applicable to safety assessments of various subsurface utilization technologies, including carbon capture and storage (CCS), underground hydrogen storage (UHS), and subsurface radioactive waste disposal. In addition, brittleness is an essential parameter in hydraulic fracturing design and sweet-spot identification for shale reservoir development. Typically, brittleness can be determined using either the mineralogical characteristics or the petrophysical properties of rocks. The mineralogical approach calculates the brittleness index based on the content ratios of constituent minerals, such as quartz and calcite. To determine the brittleness distribution based on petrophysical properties, characteristic values such as Young’s modulus and Poisson’s ratio are essential. These properties can be derived from well-logging and seismic data, enabling a comprehensive evaluation of the brittleness distribution. Although seismic data are effective for identifying petrophysical properties across extensive formations, an indirect approach limits the ability to obtain high-resolution property information. In contrast, well-logging data are directly obtained through borehole measurement instruments and provide accurate information with high resolution; however, they can only obtain local information about the area surrounding the borehole. In this study, we analyzed case studies of brittleness distribution using well-logging and seismic data. The methodologies were applied to the Volve Field dataset from the North Sea, which was released by Equinor for academic purposes. Well-logging and seismic data were integrated to predict elastic properties, including compressional travel time (DTC), bulk density (RHOB), and shear wave travel time (DTS), to derive Young’s modulus and Poisson’s ratio for the Volve Field. Based on these analyses, the regional brittle-ductile distribution in the Volve Field study area was effectively classified and evaluated.

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